travis update - have a build with and without -fno-common

sys/unix/hints/linux-travis

@@ -35,6 +35,11 @@ CFLAGS+=-DCURSES_GRAPHICS
 #CFLAGS+=-DMSGHANDLER
 #CFLAGS+=-DTTY_TILES_ESCCODES
 
+# when building liblua.a, avoid warning that use of tmpnam() should be
+# replaced by mkstemp(); the lua code doesn't use nethack's config.h so
+# this needs to be passed via make rather than defined in unixconf.h
+SYSCFLAGS=-DLUA_USE_POSIX
+
 LINK=$(CC)
 # Only needed for GLIBC stack trace:
 LFLAGS=-rdynamic